GB559021A - Improvements in or relating to electron multiplier circuits - Google Patents

Abstract

559,021. Electron multiplier circuits. FFENNELL, H. S. MOLYNEUX-, BOSCH, F. J. G. VAN DEN, and VACUUM-SCIENCE PRODUCTS, Ltd. July 28, 1942, No. 10567. [Class 40 (v)] In an electron multiplier circuit of the kind in which a source of high potential is connected across a resistance potentiometer having tapping points connected to the output electrode, secondary cathodes and primary cathode, there is provided a feed-back to the primary cathode from a point in the potentiometer which is at a greater positive potential in relation to the negative side of the source of supply than the value of the normal grid bias, and means for applying to the grid a potential relative to the negative side of the source such as to provide the required grid bias potential. As shown in Fig. 2, the primary cathode 11, secondary cathodes 16 and 18 and the anode 19 are connected to tappings on a potentiometer 20 connected across a source of potential 21 in series with a resistance 26. A second potentiometer 27 feeds the accelerator 14 and, through the tuned input circuit 25, the grid 13. The anode feeds an output circuit 22. With this arrangement, on an increase in anode current the potential of the cathodes tends to rise thus causing a further increase in anode current. However due to resistance 26, the potential across potentiometer 27 falls and the potential of the accelerator and the grid is reduced to compensate the increase in anode current and the instability is removed. The compensating effect is increased by the resistances 28, 29 between the cathode and grid. In a modification, Fig. 3 (not shown), the invention is applied to an electron multiplier used as a frequency changer in a superheterodyne receiver. In this case, the second potentiometer is dispensed with and the accelerator is connected to an independent source of constant potential. Specification 545,123 is referred to.